The manufacture of metal parts such as the half-frames of aircraft structural box assemblies is conventionally carried out by forging a preliminary blank approaching the general shape of the frame and then machining the preliminary blank in order to achieve constant thickness, quenching and pressing to obtain a final blank ready to be machined.
The manufacturing cycle also comprises, after forging, a machining operation for producing constant thickness in order to press the preliminary blank in an even manner after the quenching operation, the pressing being used to prevent deformations during machining and at the end a final machining.
The half-frames of aircraft structural box assemblies and in particular the half-frames of the central structural box assembly forming the junction between the fuselage and the wings are metal parts which comprise a relatively bulky foot in the form of a spade and a curved, elongated tail.
The conventional method mentioned above has the drawback of generating considerable wastage since, for example, for half-frames of the central structural box assembly comprising a spade that is of the order of 1300 mm long, 500 mm wide and 80 mm thick and a tail of the order of 2600 mm long and with a section of 80×80 mm curved at a radius of the order of 2000 to 3000 mm, a preliminary blank weighing approximately 450 kg is necessary to produce a part which, in the end, will weigh only approximately 30 to 50 kg.
This is due to the fact that, despite the skill of the metalworkers, the extra thicknesses necessary to produce the preliminary forge blank remain considerable.
In addition, this method takes several hours because two machining steps and one compacting step are necessary in addition to the forging step.